In the art relating to diesel engines, it is known to provide each of the cylinders in an aligned bank of cylinders with a swirl forming inlet port, including a passage extending laterally inwardly from the side of an engine cylinder head to connect with a spiral passage opening to the engine cylinder. Engines with inlet ports of this general description are shown in the prior art, for example, in U.S. Pat. No. 3,273,551 Julien et al, U.S. Pat. No. 3,874,357 List et al, and U.S. Pat. No. 3,945,349 Elsbett et al.
It has been found through experience that in engines utilizing inlet ports of this general character, the amount of swirl developed in the engine cylinders may be affected favorably or adversely by flow conditions in the manifold or piping connected to supply air to the inlet ports. In this regard, it is noted that somewhat similar port inlet conditions are provided by the relatively long individual runners of the inlet piping of U.S. Pat. No. 3,945,349 Elsbett et al and by the end fed inlet manifolding shown in FIG. 18 of U.S. Pat. No. 3,874,357 List et al. In the arrangement of U.S. Pat. No. 3,273,551 Julien et al, the guide vane 60 on the floor of the port might have the effect of correcting somewhat for variable manifold air delivery conditions.
In practical engine embodiments, it is not always possible or desirable to utilize intake piping or manifolds having long individual inlet runners or end connections to a log-type manifold; nor is it necessarily desirable to include straightening vanes or other devices within the engine intake port to control inlet flow conditions. Thus, it is desired to provide a diesel type internal combustion engine having a plurality of aligned cylinder air swirl developing inlet ports, the swirl forming qualities of which are affected by inlet gas delivery conditions, with a compact intake manifold arrangement capable of providing air to the various ports under similar gas delivery conditions that do not adversely affect the port swirl developing qualities.